The present invention relates to a process and apparatus for controlling an automatic machine for cleaning castings, in particular grinding machines for cleaning castings, by which a grinding or cutting-off disk engages on a clamped casting and then at least the operating advance of the grinding or cutting-off disk is program controlled by means of control data dependent on the workpiece.
In known processes of the aforementioned kind, noise or vibration resulting from the grinding tool touching the workpiece is employed for switching over from preparation speed to operating speed or as start signal for a program control, appropriate electric control signals being attained via vibration meters and frequency converters.
The attainment of the signal always requires, thereby, a contact between grinding disk and casting, which is contradictory to a precise control by a pre-signal. In addition, frequency-dependent measurements of the contact between grinding disk and casting are completely unsuited for aluminium castings.
Pressure force arising due to the functionally-dependent shortening of the circumferential length, which, from a critical height of lift, causes a bending-in on the edge of the cell in relation to the seam areas, and which decreases the longevity of the cell considerably. In order to counteract this, fluid cells according to the second-mentioned method of construction have been designed, whereby the tangential pressure force arising in the edge parts is at least partially eliminated by tangential traction on the convex circumferential parts. However, also this has not lead to suitable results: wherefore the effectiveness of such fluid cells based on compressed air radial motors has never succeeded in being generally adopted in spite of the many excellent qualities thereof.